import math
x1, y1, x2, y2 = map(float, input().split())
X = x1 - x2
Y = y1 - y2
print('{:.5f}'.format(math.sqrt(X * X + Y * Y)))
 import math math x1, y1, x2, y2 = map(float, input().split()) x1 map(float, input().split()) map float input().split() ().split () input split y1 x2 y2 X = x1 - x2 X x1 - x2 x1 x2 Y = y1 - y2 Y y1 - y2 y1 y2 print('{:.5f}'.format(math.sqrt(X * X + Y * Y))) print '{:.5f}'.format(math.sqrt(X * X + Y * Y)) '{:.5f}'.format '{:.5f}' format math.sqrt(X * X + Y * Y) math.sqrt math sqrt X * X + Y * Y X * X X X Y * Y Y Y x1, y1, x2, y2 = map(float, input().split()) map(float, input().split()) x1 y2 = map(float, input().split()) map(float, input().split()) y2 y1, x2, y2 = map(float, input().split()) map(float, input().split()) y1 x2, y2 = map(float, input().split()) map(float, input().split()) x2 X = x1 - x2 x1 - x2 X Y = y1 - y2 y1 - y2 Y
import math
x1, y1, x2, y2 = map(float, input().split())
X = x1 - x2
Y = y1 - y2
print('{:.5f}'.format(math.sqrt(X * X + Y * Y)))

